Try Delta
Delta will match F9 Summit to their Silver Medallion status if you fly 6250 miles or have 8 segments in 90 days on their metal after the match.
At delta.com, search for SKYMILES MEDALLION® STATUS MATCH CHALLENGE.
I have six segments so far, but no First Class upgrades have cleared. You can upgrade to Econ. Comfort at check-in for free, which I have done. You also get a free bag and the priority check-in/boarding.
They support PreCheck too, which is great. Only hassle is you almost always have to connect in SLC or ATL to get anywhere else.
How did you get the UA Status Match, if you don't mind sharing?